They start with whole sub-primals-large cuts of meat with bones and fat caps fully intact, aging them uncovered in temperature, humidity, and air speed-controlled rooms designed to allow them to age for weeks or months without rotting.

Serious Eats illustrates how you can do this at home, with relatively little effort. Ideally, you'll be using a dedicated mini-fridge with a fan in it, but you might be able to accomplish something close in your regular fridge. In typical Kenji fashion, the tutorial is full of scientific reasons why your DIY aged meat will be the most flavorful and rewarding piece of beef you've ever tasted.